Modern data centers can have a huge number of individual computing servers, with some larger data centers having tens of thousands of computing servers or even more. These data centers are often designed so that user-experienced time delay between actions and effects (called “latency”) is acceptable at times of maximum data center usage (called “peak times”). As a result, data centers often have over-capacity during non-peak times, meaning the data centers have computing resources that are under-utilized during the non-peak times.
Due to the large numbers of computing servers in modern data centers, those data centers consume an enormous amount of power. It has been estimated that current data centers are collectively responsible for consuming approximately 3% of the world's electricity, and it is estimated that the consumed power will double in the next five years. The cost of electricity is one of the limiting factors in the performance and profitability of a data center. Because of this, data center owners often wish to reduce their electricity usage while preserving the performance of their data centers.
Unfortunately, modern data centers and servers are becoming more and more complex. For example, in one conventional data center energy management approach, each computing server can be placed into one of seven different states corresponding to seven different active/standby modes. While these modes have the potential to assist in power management, there is a tradeoff between using power saving states while still preserving the ability to respond to user demands. Moreover, the complexity of a data center and the complexity of the data center's servers complicate attempts to manage operations of the data center.